Christopher Wray, President Donald Trump’s nominee to lead the Federal Bureau of Investigations, said Wednesday that he did not consider the probe into alleged Russian interference in the 2016 election to be a “witch hunt,” disagreeing with the president’s own assessment of the matter.

“I do not consider Director Mueller to be on a witch hunt,” Wray said, referring to Special Counsel Robert Mueller, during a tense exchange with Sen. Lindsay Graham, R-S.C., during his confirmation hearing Wednesday before the Senate Judiciary Committee.

The president tweeted Wednesday morning that the investigation, which includes probing allegations of collusion between Russia and Trump’s campaign, “is the greatest Witch Hunt in political history.”

Wray, who was tapped by Trump in June to replace fired former FBI Director James Comey, faced questions on a range of issues, with senators grilling the former justice department official over how he would distinguish himself from Comey as well as his ability to lead the agency and high-profile investigations without fear or favor.

Wray addressed his commitment to an independent FBI in his opening remarks.

“If I am given the honor of leading this agency, I will never allow the FBI’s work to be driven by anything other than the facts, the law, and the impartial pursuit of justice. Period. Full stop,” Wray, 50, said at the start of the hearing. “My loyalty is to the Constitution and the rule of law.”

“Anybody who thinks I would be pulling punches, sure doesn’t know me very well,” he added after Sen. Chuck Grassley, R-Iowa, who chairs the committee, pressed him again on the independence question.

“I believe to my core that there’s only one right way to do this job and that is with strict independence,” Wray added.

Ranking member Sen. Dianne Feinstein, D-Cali., asked Wray if he would alert the committee if there were “any efforts to interfere” with Mueller’s Russia investigation, which NBC News has reported is looking into whether President Trump attempted to obstruct justice.

Wray, who called Mueller “the consummate straight shooter, said he was “very committed” to supporting Mueller and would do everything he could legally to inform the committee of any attempts.

Committee members also asked how Wray would differ from his predecessor and former colleague Comey, whose unceremonious firing in May sent shockwaves throughout the Beltway and beyond, intensified the focus on the ongoing investigations into Russian meddling in the 2016 election and renewed focus on how Comey’s successor would carry out the role.

In the wake of his firing, Comey testified before the Senate Intelligence Committee that Trump asked him for a loyalty pledge and believed the president wanted him to drop the FBI’s investigation into Michael Flynn, the president’s former national security adviser.

Sen. Patrick Leahy, D-Vt., asked Wray if he had been asked to give any sort of loyalty pledge from the White House.

“No one asked me for any sort of loyalty oath at any point during this process and I sure as heck didn’t offer one,” Wray said.

Graham read out portions of the exchange, which Trump Jr. released publicly Tuesday, that show Goldstone arranging a meeting with a Russian lawyer promising “information that would incriminate Hillary and her dealings with Russia and would be very useful to your father” that was “part of Russia and its government’s support for Mr. Trump.”

Wray said he was not familiar with the details of Trump Jr.’s emails, which led to a June 9, 2016 meeting at the Trump Tower between Trump Jr., Goldstone and the Russian lawyer, Natalia Veselnitskaya. Jared Kushner, the president’s son-in-law and a current White House adviser and Paul Manafort, Trump’s then-campaign chair, also attended the meeting.

Graham then pressed Wray on whether the FBI should have been called prior to the meeting. Wray tried to side-step the question, prompting the senator to shoot back: “You’re going to be the director of the FBI pal, so here’s what I want you to tell every politician, if you get a call from somebody suggesting that a foreign government wants to help you to by disparaging your opponent, tell us all to call the FBI.”

Wray replied: “Any threat or effort to interfere with our elections … is the kind of thing the FBI wants to know.”

“That is a great answer,” Graham said.

Wray, a former federal prosecutor, was nominated by former President George W. Bush to led the justice department’s criminal division in 2003, where he worked closely with Comey. The Senate unanimously confirmed his nomination.

He left the department in 2005 and returned to private practice as a white-collar criminal defense attorney. He currently works for Spalding & King, an Atlanta-based legal giant where he began his career in 1993. He also represented New Jersey Gov. Chris Christie in the Bridgegate scandal.

As FBI director, Wray would be responsible for leading a team of more than 30,000 FBI employees scattered across 56 U.S. field offices.

He said Wednesday that he received word of his consideration after being contacted by phone by Deputy Attorney General Rod Rosenstein the day after Memorial Day, which was followed up with an in-person meeting at the White House with Rosenstein and Attorney General Jeff Sessions and then meetings with other White House officials and President Trump.

“Both meetings were very conversational. It was more a get-to-know-you conversation,” he told senators.

“I would say I went into both meetings listening very carefully to make sure that I didn’t hear something that would make me uncomfortable. … If anything was said that made me uncomfortable I would not be sitting here today speaking in favor of my nomination,” he added.

Wray said during the conversations, the Russia investigation and Comey’s firing did not come up, except when Rosenstein mentioned Mueller was leading the investigation, which he said he believed would take pressure off the director role.

“I was very comfortable that I would be able to do my job,” he told the senators.

During and after the hearing, which lasted more than four hours, senators on both sides of the aisle offered glowing reviews of his testimony.

“Well, I’ll be very candid with you. I’m going to vote yes. I see him as being a good FBI director, how good the proof is always in the pudding,” said Feinstein. “I think in this man we have somebody who understands the process of justice who is committed to the appropriate and positive process.”

Sen. Amy Klobuchar, D-Minn., and Blumenthal also said they would support his nomination.

Klobuchar said Wray “had a lot of support here” and found his answers to remain independent and uphold the law “very compelling and heartfelt.”

Blumenthal said Wray would bring “guts and backbone” to the FBI.

Grassley, the Republican committee chair, said he expects to move the nomination quickly, but did not give a time frame.

“I think we can get this done very quickly even without the two additional weeks of session this summer,” he said.